// Set these to how you want inline and display math to be delimited.
const defaultCopyDelimiters = {
    inline: ['$', '$'],
    // alternative: ['\(', '\)']
    display: ['$$', '$$'] // alternative: ['\[', '\]']

}; // Replace .katex elements with their TeX source (<annotation> element).
// Modifies fragment in-place.  Useful for writing your own 'copy' handler,
// as in copy-tex.js.

const katexReplaceWithTex = function katexReplaceWithTex(fragment, copyDelimiters) {
    if (copyDelimiters === void 0) {
        copyDelimiters = defaultCopyDelimiters;
    }

    // Remove .katex-html blocks that are preceded by .katex-mathml blocks
    // (which will get replaced below).
    const katexHtml = fragment.querySelectorAll('.katex-mathml + .katex-html');

    for (let i = 0; i < katexHtml.length; i++) {
        const element = katexHtml[i];

        if (element.remove) {
            element.remove(null);
        } else {
            element.parentNode.removeChild(element);
        }
    } // Replace .katex-mathml elements with their annotation (TeX source)
    // descendant, with inline delimiters.


    const katexMathml = fragment.querySelectorAll('.katex-mathml');

    for (let i = 0; i < katexMathml.length; i++) {
        const element = katexMathml[i];
        const texSource = element.querySelector('annotation');

        if (texSource) {
            if (element.replaceWith) {
                element.replaceWith(texSource);
            } else {
                element.parentNode.replaceChild(texSource, element);
            }

            texSource.innerHTML = copyDelimiters.inline[0] + texSource.innerHTML + copyDelimiters.inline[1];
        }
    } // Switch display math to display delimiters.


    const displays = fragment.querySelectorAll('.katex-display annotation');

    for (let i = 0; i < displays.length; i++) {
        const element = displays[i];
        element.innerHTML = copyDelimiters.display[0] + element.innerHTML.substr(copyDelimiters.inline[0].length, element.innerHTML.length - copyDelimiters.inline[0].length - copyDelimiters.inline[1].length) + copyDelimiters.display[1];
    }

    return fragment;
};

document.addEventListener('copy', function (event) {
    const selection = window.getSelection();

    if (selection.isCollapsed) {
        return; // default action OK if selection is empty
    }

    const fragment = selection.getRangeAt(0).cloneContents();

    if (!fragment.querySelector('.katex-mathml')) {
        return; // default action OK if no .katex-mathml elements
    } // Preserve usual HTML copy/paste behavior.


    const html = [];

    for (let i = 0; i < fragment.childNodes.length; i++) {
        html.push(fragment.childNodes[i].outerHTML);
    }

    event.clipboardData.setData('text/html', html.join('')); // Rewrite plain-text version.

    event.clipboardData.setData('text/plain', katexReplaceWithTex(fragment).textContent); // Prevent normal copy handling.

    event.preventDefault();
});
